Described herein are scanners for scanning wafers, methods for scanning wafers using the scanners, and components of the scanners, wherein the scanner may be, for example, a hydrophilic bulk bevel scanner.
Semiconductor fabrication is a multi-step manufacturing process including, for example, cleaning (e.g. using weak acids to remove unwanted particles), deposition (e.g. physical vapor deposition (PVD), chemical vapor deposition (CVD), and electromechanical deposition (ECD)), removal processes (e.g. wet etching, dry etching, and chemical-mechanical planarization (CMP)), patterning (e.g. lithography), and modification of electrical properties (e.g. doping and ion implantation). In an exemplary phase deposition processes, a vaporized chemical (e.g. SiH4, SiH2Cl2, SiHCl4, SiCl4, Si2H6, etc.) may be condensed onto a wafer (also referred to as a substrate or a slice). The finished semiconductors are then separated (e.g. using dicing) into individual microcircuits for use in the fabrication of microelectronic devices, including but not limited to integrated circuits, solar devices, LEDs, flash, DRAM, memories.
Even in very small proportions, the presence of contaminants (e.g. heavy metals, oxides, nitrides, etc.) on wafers may decrease and/or destroy the function of downstream microelectronic devices. Generally at least one wafer per batch of wafers is tested for the presence and/or quantity of contaminants as part of the manufacturing process.
In order to test for contaminants on a wafer, a liquid may be brought into contact with the surface of the wafer. If contaminants are present on the wafer surface, at least some of the contaminants will be diffused or otherwise transferred into the liquid. After the liquid contacts the wafer surface, it may then be analyzed for the presence of contaminants. If contaminants are found on a wafer, the batch may be pulled from distribution or cleaned to prevent issues in functionality of downstream microelectronic devices.
One method and device for testing for contaminants on a wafer is described in Japanese Patent No. JP2012-9475A. This reference describes the use of a droplet of liquid, such as a droplet of hydrogen fluoride (HF), being placed on an upper surface of a wafer held in horizontal orientation. During contaminant testing, the droplet is moved across the upper surface of the wafer. The droplet is then collected and analyzed for the presence of contaminants. This method and device may be problematic in that the droplet may spread out and/or adhere to the surface of the wafer if the wafer is hydrophilic, making collection and analysis of the drop difficult. Further, the wafer may only be analyzed in a horizontal position and therefore only a bulk (i.e. planar surface) portion of the wafer is tested for contamination. Further still, the movement pattern of the droplet may be unpredictable and sample from only a small portion of the wafer surface.
In another method and device for testing for wafer contamination from the non-patent literature publication “A Novel Technique for Contamination Analysis of the Edge, the Bevel, and the Exclusion Area of 200 and 300 mm Silicon Wafers” by Chris Sparks et al. from International SEMATECH (hereinafter referred to as “Sparks”), a wafer is held in a vertical orientation. A sample boat containing liquid may be raised to the edge of the wafer so that the wafer is at least partially submerged into the liquid within the sample boat, below an upper edge of the sample boat. The liquid is then collected in a 0.5 mL sample vial and analyzed by a scanning device (Technos 630T nine point TXRF analysis). This method and device may be problematic in that it requires a relatively large liquid sample, which may be a hazardous material. Further, the wafer may only be analyzed in a vertical orientation and, therefore, only the beveled edge and/or surfaces close to the beveled edge of the wafer will be tested for contamination.